The overall objective of this research is the production of dimer-specific antibodies and the development of immunohistological techniques for screening and identification of high risk, nonxeroderma pigmentosum (XP) individuals especially in families with a higher than normal susceptibility to skin carcinogenesis. Radioimmunoassays (RIAs) will be developed to distinguish between ultraviolet radiation (UVR)- induced thymine-thymine, thymine-cytosine and cytosine-cytosine dimers. The antibodies specific for pyrimidine dimers will be incorporated into immunohistological procedures that will allow the rates of induction, distribution and fate of DNA damage to be measured in mouse epithelial cells exposed in vivo to UVR on the presumption that the risk of cutaneous carcinoma in a "normal" or non-XP population may be related to the ability to repair damaged DNA.